I've been ordering 15.5" shirts from Jantzen, and also wear that size OTR. However, I've noticed that I can fit more than two fingers into my buttoned collar, and I'm wondering if my collar is a dab loose. From experience, I know that a 15" would be too tight, but could I go with a 15.25"? I'm wondering how much tighter that quarter inch will make the collar, because I don't want to do another test shirt from Jantzen but also don't want to be left with a bunch of shirts I can't button. Thanks.